I use the backup tool arq to backup my data from my computers to the cloud.
With arq you only buy the backup software. So you can choose and switch the cloud provider as you like. Arq exists for Mac and Windows.
Where to store the data
Arq support a lot of cloud storage provider here a list of the supported providers:
Amazon Cloud Drive
Google Nearline Google Coldline Wasabi
It also support sftp conection to do a ssh server or to backup to a local folder on your disk or nas.
Arq encrypt all your data on yor computer before transmit them to the cloud. First you have to enter the encryption key. The key will not be stored in the cloud.